What does the kinetic theory say about the kinetic energy present in solids

The kinetic energy of solids is limited to vibrational energies..the particles are tightly bound in their crystalline structure and can only bend, flex, and vibrate about relatively fixed position.  When vibrational energies exceed the strength of the force holding the particles together, the crystal structure collapses and we say the material melted.  The particles can now have, in addition to its vibrational energies, rotational energy.  Chunks of the collapsed crystal can, like a ball floating in water, rotate without showing much translational energy. Generally, we associate solids with vibrational kinetic energy, liquids with rotational kinetic energy, and gases with translational kinetic energy. Actually though, liquids have both vibrational and rotational energies, and gases have all three.

The number of O atoms in 7.3 x10 ^-3 g of CaSO4 x 2H2O  are

= 1.535 x10^20  atoms

calculation

step 1: calculate the moles of CaSO4 . 2H2O

moles = mass/molar mass

molar mass is of CaSO4.H2O=Mw of Ca + S +O +H2O

= 40+32 +( 4x16)  +2( (1x2)+16)=  172 g/mol

moles is therefore= 7.3 x10^-3 g/172 g/mol=   4.244  x10^-5 moles

find the moles of O

since there are 6 atoms of O the moles of O=   6 x ( 4.244 x10^-5)= 0.000255 moles

by use  of Avogadro's law constant find the number of O atom

that is  1 mole     =       6.02 x10 ^23 atoms

                     0.000255 moles=? atoms

by cross multiplication

= 0.000255 moles  x(6.02 x10^23 atoms)/ 1 mole=  1.535  x10^20 atoms